LIVE OAK COUNTY -- Two Swinney Switch volunteer firefighters who were injured early Wednesday when their truck flipped over on the way back from a fire were treated and released from area hospitals and had returned to work by Friday, authorities said.

"They are both back on duty," confirmed Lonnie Messer, chief of the Swinney Switch Volunteer Fire Department "The Good Lord was riding with them that night."

The accident took place about 4 a.m. Wednesday. Both men --who the chief declined to immediately name but said were 75 and 68 years old --were injured while returning from fighting a 1:30 a.m. structure fire in Lagarto.

The firefighters were north of Orange Grove when the 2009 Peterbilt tanker truck, in which they were traveling, flipped over, reports show.

"It happened as they were coming down FM 534 where it meets FM 1362," the chief said. "They were going a little fast around the curb on the edge of the sand and they flipped the truck."

It is possible that exhaustion from duty played a part in the accident, the chief said.

The 75-year-old firefighter was flown to Christus Spohn Hospital Memorial in Corpus Christi. The 68-year-old firefighter was taken by ground ambulance to a Beeville hospital.

"They airlifted one of them because they thought he was in bad shape," the chief said. "But they examined him and everything turned out to be all right. He was just bruised. The other got sent to Beeville with a knot on his head -- he was also bruised up."

The two firefighters each were released from the hospitals hours after they were admitted.

Messer said the two remain sore and bruised from the incident.

"As they rolled they hit their heads on windows and such and were really banged around," the chief said.

Messer described the two as veteran volunteer firefighters -- one with 15 years and another with two years of service to the department.

The truck, meanwhile, sustained $15,000 to $20,000 worth of damage. When the chief spoke to a reporter Friday, he was in the process of waiting for an adjustor to come and evaluate the damaged vehicle.

There are 25 volunteer firefighters in the Swinney Switch department, the chief said.